Previous in vitro and in vivo studies have shown that an intraoral fluoride releasing-device developed by the Southern Research Institute for the National Caries Program will deliver fluoride at a steady rate for up to six months. This project will evaluate the anticaries effect and mechanism of action of the fluoride-releasing device in rats. Results have shown that rats that had an intraoral fluoride releasing device in their mouth developed significantly fewer caries on all surfaces than untreated or placebo treated animals. The data indicate that the marked caries reduction produced by the fluoride releasing device was due to topical effects of fluoride. Additional data suggest that the cariostatic effects of the intraoral fluoride-releasing device may persist for a significant time period after the device is removed from the mouth.